Heterocyclic nitrogen compound containing antimony plating solutions and process



United States Patent HETEROCYCLIC NITROGEN COMPOUND CON" TAININGANTIMONY PLATING SOLUTIONS AND PROCESS Arthur H. Du Rose, Euclid, Ohio,assignor to The Harshaw Chemical Company, Cleveland, Ohio, 21corporation of Ohio No Drawing. Application November 7, 1955, Serial No.545,569

' 28 Claims. (Cl.20445) This invention relates to the electrodepositionof antimony, most particularly from solutions wherein the antimony ispresent as a soluble fluoride. Specifically, the invention relates tothe use of heterocyclic amines in antimony fluoride containing platingsolution for the purpose of increasing the brightness of the depositobtained therefrom.

It is an object of the invention to provide a process and platingsolution for the electrodeposition of antimony from antimony fluoridesolutions containing one or more compounds which add to the luster ofthe deposit obtained therefrom. It is a further object to provide fornew and novel antimony plating processes and solutions containingcompounds which enhance the brightness of the deposits obtainedtherefrom. It is a further object to provide for a new and novel processof electroplating from antimony fluoride containing solutionscharacterized by the incorporation therein of one or more compoundswhich enhance the brightness of the plate obtained therefrom. It isstill another object to provide for cooperating addition agents forantimony fluoride containing plating solutions, which addition agentsdecrease the amount of misplating and promote greater uniformity ofcolor in the plates obtained therefrom. Other and further objects willbe apparent from the following description and disclosure.

The invention is specifically directed to the use of antimony platingsolutions wherein the antimony is primarily present therein as a solublefluoride. Specific examples of plating solutions to which referenceherein is had will be found in the Bloom U. S. Patent No. 2,389,131, andin my co-pending application U. S. Serial No. 303,160, filed August 7,1952, and entitled Electrodeposition of Antimony. The fundamentalplating bath should be an aqueous acid solution of an antimony compound,such as antimony trifluoride. Such baths may also utilize one or morecompounds for adjusting the pH of the solution as well as chemical meansfor holding the antimony in solution. The pH may be adjusted by the useof am-v monium hydroxide or carbonate or, less desirable, by the use ofsodium or potassium hydroxide or carbonate. An amine, such astriethanolamine, may also suitably be used for adjusting the pH.Precipitation of the antimony fluoride should be prevented so thatsuitably about 0.7 mol and, preferably, up to about 1.5 mols of antimonytrifluoride per liter are present therein under most of the preferredoperating conditions. The precipitation of the antimony fluoride may beprevented by utilizing such alpha-hydroxy carboxylic acids as tartaric,citric, gluconic, glycolic or lactic, or by the ammonium, sodium orpotassium or amine salts thereof. An excess of the halogen ion is alsosuitable for this purpose. In the event that salts of the alpha-hydroxycarboxylic acids are employed, the salts can be utilized simultaneouslyas a means or partial means for adjusting the pH of the solution. Forexample, antimony trifluoride, ammonium gly- ICC colate and Water make afundamental bath in which the addition agents according to the inventionmay be used.

Although it is preferred that the antimony be present in the form of itsfluoride, antimony trichloride may be substituted in part for theantimony fluoride in the bath. For example, up to about 40% by weight ofthe antimony content may be present as the chloride. In this event,however, it will still be recognized that the antimony is present in thebath primarily as the soluble fluoride.

When alpha-hydroxy carboxylic acids are employed for preventing theprecipitation of antimony fluoride, the quantity thereof may be Withinthe range of about /s to 2 hydroxy equivalent weights of the acid peratomic weight of antimony, the preferred concentration being about onealpha-hydroxy equivalent weight of acid per atomic Weight of antimony.(By alpha-hydroxy equivalent weight, it is meant the molecular weight ofthe alphahydroxy acid divided by the number of its alpha-hydroxygroups.)

As a measure for insuring against immersion deposition of the antimonyupon the cathodes, it is highly desirable that sulfate ion be present inthe solution. When used, the concentration of the sulfate ion should befrom about 50 to mol percent of the alpha hydroxy acid. Obviously thesulfate ion is not an essential ingredient in the bath but is merelyhighly. desirable for the purpose of preventing immersion deposition ofthe antimony on the cathodes.

In making up. the fundamental plating bath, the adjustments of the pHmay be accomplished or partly so by the choice of compounds. Thus, forexample, by using antimony trioxide (SbzOa) and an acid ammoniumfluoride (NH4HF2), antimony trifluoride (SbF3) is produced in situ inthe bath or in the tank used for manufacture of concentrates thereof.Additional alkaline material may or may not be needed to secure thedesired pH. As a practical matter, it is very desirable to form a bathof a concentration which requires little or very little addition ofammonia to the plating tank. It is also proper to make use of antimonyoxide and ammonium bifluoride instead of using antimony trifluoride assuch in making baths or concentrates. Preferably, the solutions consistof antimony oxide, acid ammonium fluoride and glycolic acid inproportions to yield antimony trifluoride and ammonium glycolate at pHsfrom .5 to 2.0 with additional ammonium hydroxide to yield a pH 2.5 to5.0.

According to the invention, it has been discovered that heterocyclicamines when employed with cooperating aromatic sulfonamides andderivatives thereof such as the sulfonimides, which are consideredherein as encompassed in the term sulfonamides, are especially suitablefor improving the luster of deposits obtained from antimony platingsolutions wherein the antimony is present primarily as the solublefluoride. Alone, the heterocyclic amines do not appear to enhance thelustrous nature of antimony deposits. However, when utilized with whatmay be termed as cooperating brightening agents, it appears that theymaterially increase the brightnem of the deposit obtained. In general,the use' of the heterocyclic amines with one or more cooperating agents,such as those of the aromatic sulfonarnide types are productive ofbright deposits, although occasionally only semi-bright finishes areobtainable. In every instance of the compounds tried,'however, it hasbeen found that the heterocyclic amines enhanced the lustrous nature ofthe deposit obtained from the aforementioned fluoride containing bathsabove and beyond the nature of the deposits usually obtained without theemployment of the novel additives. In addition to the novel combinationsof aromatic sulfonamides and heterocyclic amines within the scope of 3.the invention, it has been found that copper, coumarin and zincadditions impart further advantages in the form of still increasedbrightness, and/or leveling and/or deposit uniformity.

It has been found that these compounds of the aromatic sulfonamide typeare especially suitable for use with the heterocyclic amines of theherein described invention. Especially beneficial results have beenobtained when the aromatic sulfonamides utilized according to the hereindescribed invention are selected from the following class ofsulfonamides:

Benzene sulfonamide CsHSO2NHz Toluene sulfonamide CHsCsHsSOzNHnDi-benzene sulfonamide CsHsSOzNHSOaCBHs Di-benzene sulfonamide etherAlthough the aforementioned sulfonamide derivatives of benzene arepreferably employed as cooperating brightening agents according to theinvention, it will be apparent that other sulfonamides of the aromaticclassification may be employed with beneficial results, for example,sulfonamide derivatives of naphthalene. Aromatic sulfonates andsulfinates have been found to have a cooperating action with theheterocyclic amines. Inmany instances, however, results obtainedtherefrom have been considerably less satisfactory than the resultsobtained with the sulfonamides in that misplating and other commonplating difliculties occur. For example, saccharin has been employed asa cooperating brightening agent with the aromatic amines but withconsiderably less success than that found with the benzene sulfonamidetype compounds.

Examples of the heterocyclic amines which have been found especiallybeneficial in their cooperating brightening action with the benzene typesulfonamides are pyridine and salts thereof,

di-pyrldyl and salts thereof,

B-naphthoquinoline and salts thereof,

N CH:

di-methyl quinoline and salts thereof, as well as such specificheterocyclic amines as CH3 (osotoud- N-methyl qulnollum methosulfateN-methyl-2-carboxy quinolinium methyl sulfate Other heterocyclic aminesmay be employed with cooperating brightening results and accordingly,the invention is not be be construed as limited to the specificheterocyclic amines set forth heretofore, except as provided by theclaims. It will be noted that the heterocyclic amines described have atleast one 6-membered ring and may be described generically asheterocyclie nitrogen containing compounds having at least one6-membered ring.

Preferably the cooperating aromatic sulfonamides are employed in amountsranging from 0.25 to about 6 grams per liter. In certain circumstances,however, it may be desirable to employ the aromatic sulfonamides inamounts in excess of 6 grams per liter for the most beneficial result,although it, hasgenerally been determined that quantities thereoffalling within the range heretofore given will produce the greatestbrightness when utilized with the heterocyclic amines in their preferredquantities.

When employed with the aromatic sulfonamides in the preferred amounts,the heterocyclic amines have been found to produce the greatestbrightness and most lustrous deposits in amounts ranging generally fromabout .01 to about 3.5 grams per liter thereof. In certain circumstancesit may be found desirable to operate outside of this range, that is, forexample, to employ greater amounts of the heterocyclic amines to obtainthe most beneficial over-all results from the plating solution and,accordingly, the invention is not to be construed as limited to thespecific ranges except as specifically set forth in the claims appendedhereto.

The following are specific examples. showing the cooperating brighteningaction attributed to the combination of aromatic sulfonamides andheterocyclic amines falling within the scope of the invention. In eachcase the aromatic sulfonamides and heterocyclic amines were added to anaqueous antimony plating solution which consisted of the followingingredients:

Grams per liter Sb2O3 180 NH4FHF Glycolic acid 133 NH4SO4, 162

Example N0. 1

Grams per liter Toluene sulfnnamide 2 Di-pyridyl .05

The panel obtained showed a bright antimony deposit.

Example No. 2

Grams per liter Di-benzene sulfonamide 1 Pyridine .5

The panel plated had a bright finish and when the pyridine concentrationwas raised to one gram per liter, the panel obtained was also bright.

Example N0. 3

Grams per liter Bi-di-benzene sulfn mide 2 .Di-pyridyl .02 Pyridine .2

The panel obtained had a bright finish. A similar result was obtainedwhen the pyridine concentration was .4 gram per liter and the di-pyridylconcentration was .0025 gram per liter. Similar results were againobtained when the pyridine concentraton was .8 gram per liter and thedi-pyridyl concentration was .005 gram per liter.

Example N0. 4

, Grams per liter Di-benzene sulfonamide 1 N-methyl quinoliniummethosulfate .025

A bright finish was obtained on the plate and similar results wereobtained when the concentration of the heterocyclic'amine was increasedto about .130 gram per liter.

Example No. 5

Grams per liter Di-benzene sulfonamide 2 ,B-Naphthoquinoline .09

In this case the plate obtained was bright and the brightness was stillproduced when the concentration of the B-naphthoquinoline was doubled. Areduction in the amount of the B-naphthoquinoline to .05 gram per literdecreased the brightness to the point where it was comparable with usualcommercial semi-bright finishes.

Example No. 6

Grams per liter Di-benzene sulfonamide l 2,6-dimethyl quinoline .05

The plate obtained in this case was bright and similar results wereobtained when the concentration of the dibenzene sulfonamide was but .5gram per liter. A good bright deposit was'also obtained when thedi-benzene sulfonamide concentration ranged from .5 gram per liter to 1gram per liter and the 2,6-dimethyl quinoline concentration ranged from.05 gram to .1 gram per liter.

Example N0. 7

Grams per liter Di-benzene sulfonamide 1 N-methyl-Z-carboxy quinoliniummethyl sulfate .05

The plate in this specific case was semi-bright, yet more lustrous thanplates obtained from the antimony bath without the cooperating additionagents.

Example N0. 8

Grams per liter Di-benzene sulfonamide l N-methyl quinaldinemethosulfate .05

The plate obtained in this case was bright and similar results wereobtained when the heterocyclic amine concentration was raised to .125gram per liter.

Of the aromatic sulfonamides set forth heretofore, it has been foundthat di-benzene sulfonamide is the preferred cooperating brighteningagent utilizable with the heterocyclic amines. The best results withthis sulfonamide (dibenzene sulfonamide) appear to be obtained when theconcentration thereof falls from about .25 to 3 grams per liter.

Of the heterocyclic amines heretofore referred to, pyridine,2,6-dimethy1 quinoline and N-methyl quinaldine methosulfate anddi-pyridyl have been found to be especially effective when employed withthe preferred amounts of di-benzene sulfonamide. In this regard,concentrations of the, four aforementioned heterocyclic amines should bewithin the range of about .01 to 1.0 gram per liter.

As a separate and distinct phase of the herein described invention, ithas been found that small additions of a soluble copper salt such as thechloride, fluoride or sulfate to the plating solution produces anexceptional luster in the plate obtained from solutions incorporatingthe aromatic sulfonamides and heterocyclic amines of the presentinvention. Although the copper imparts superior brightness when utilizedwith the combinations heretofore set forth, exceptionally bright platesare obtained whenthe copper is employed with di-benzene sulfonamidewithin the range of about .75 to 1.5 grams per liter as used incombination with N-methyl-quinolinium methosulfate and/ or N-methylquinaldine methosulfate in amounts ranging from about .01 to .20 gramper liter. In these specific combinations it has been found that themost beneficial results are obtained when the copper is employed inamounts ranging from about .003 to .1 gram thereof per liter as themetal. In general, and with reference to applications utilizing thecopper in combination with other aromatic sulfonamides and otherheterocyclic amines, the amount of copper may fall without theaforementioned range set forth for the preferred combinations but itwill be found that optimum results are usually obtained when the copperconcentration is less than about 2 grams per liter.

Specific examples of the preferred aromatic sulfonamides, heterocyclicamines and copper combinations are set forth in Examples No. 9 and N0.10 which follow. In Examples No. 9 and No. 10, the antimony fluoridebath and operating conditions were essentially the same as the bath setforth heretofore.

Example N0. 9

Grams per liter Di-benzene sulfonamide u 1 N-methyl quinoliniummethosulfate .025 Copper .025

Example N0. 10

Grams per liter Di-benzene sulfonamide 1 N-methyl quinaldinemethosulfate .05 Copper .0125

The plates obtained in this particular case were again very bright,showing substantially the same benefits as set forth in Example No. 9.It should be noted that the brightness of the plate was considerablyreduced when an identical bath was run without the addition of theheterocyclic amine set forth in the example.

Although combinations of the heterocyclic amines and aromaticsulfonamides generally within the ranges heretofore set forth producebright plates, it has been found occasionally that only semi-brightplates are produced which although being of an increased lustrous natureare less desirable than the bright plates. It is obvious that theultimate goal in most plating situations is the production of a verybright plate so as to eliminate any butting otherwise necessary for theattainment of this result. In this regard, it has been found that smalladditions of coumarin have materially affected the brightness of theplate obtained, such that the semi-bright plating solutions utilizingthe combinations of aromatic sulfonamides and heterocyclic aminesaccording to the herein described inventions may be converted intobright plating solutions. Although additions of coumarin and derivativesthereof appear to be generally beneficial when employed withcombinations of di-benzene type sulfonamides and generally heterocyclicamines, when utilizing di-benzene sulfonamide, pyridine and/ orN-methyl-Z-carboxy quinolinium methyl sulfate, and coumarin, it ispreferable to employ these addition agents in amounts ranging from about.75 to about 2.5 grams per liter for the sulfonamide, about .01 to 1.5grams per liter for the amine and about .03 to .35 gram per liter forcoumarin.

Specific examples showing the beneficial results derived from coumarinadditions in these situations are shown in Examples 11 and 13. Theantimony plating solution and conditions of operation were substantiallythe same as those described heretofore.

Example No. 11

Grams perliter Di-benzene sulfonamide 2 Pyridine 1.5

In this specific case the deposit. was semi-bright and it was found thatby the addition of .2 gram'per liter ofcoumarin a bright, uniform-plate.was obtained.

Example N 0. 12

Grams per liter Di-benzene sulfonamide 2 N,N -(oxydiethylene)-bisisoquinolinium .01

In this case the deposit obtained was semi-bright and it was found theaddition of,0;l gram per liter of coumarinmaterially increased thebrightness of the plate.

Example N; 13

Grams per liter Di-benzene sulfonamide 1 N-methyl-Z-carboxy quinoliniummethyl sulfate .15

The plate here was again semiwbright and it was found that by theaddition of .1 gram per liter of coumarin, a bright uniform plate wasobtained.

Occasionally it has been found'inattemptingto obtain abright plate bythe cooperating actionofthearomatic sulfonamides and heterocyclic aminesthatmisplating occurs. In such'situations, it has been foundthat theaddition of a soluble zinc salt, such as zinc fluoride, chloride, orsulfate substantially overcomes this problem and that furthermore, thezinc contributes appreciably to the covering power of the solution andthe leveling power thereof. In this regard it has been found thatadditions of zinc, generally within the range of about .03 to 3.5 (asthe metal) gramsiper liter, are especially elfective in obtaining thedesired result. Occasionally. a zinc ion concentration in excess of thisamount may be desirable and accordingly,

the invention is not to..be construed as specifically limited to therange of zinc heretofore set forth. A particularly desirableconcentration of ingredients is one wherein the aromatic sulfonamide isdi-benzene sulfonamide utilized in amounts ranging from 0.25t0 6 gramsper liter, the heterocyclic amine beingemployed in amounts ranging from.01 to 2 grams per liter. Specific examples of this combination are setforth hereinafter. The antimony plating-solution andconditionsweresubstantially the same as those heretofore referred to.

Example No. 14

Grams per liter Di-benzene sulfonamide Di-pyridyl .05 Zn (as metal) 1.9-

The plate obtained in this case was a brightplate and exhibited auniform color. Additions of di-pyridyl to .11 gram per liter increasedthe brightness of the plate, whereas without the di pyridyl in'theplating bath a gray deposit was obtained.

Example N0. 15

Grams per liter Di-benzene sulfonamide ether 2 Di-pyridyl .025 ZnFz .63

The plate obtained-from this particular solution was a bright platewhich showed a uniform color and deposit thereon.

From the foregoing disclosure, it is apparent that heterocyclic aminesare especially beneficial when'employed with:

Furthermore, it-is apparent that various combinations of theheteroeyclie amines and of the various aromatic sulfonam ides maybeemployed for producing the desired results. Thus a plurality of thesulfonamid'esmay be utilized in a-b'ath with one or' more heterocyclicamines and vice versa.

7 In general, the current density of the plating operation does notappear critical to the obtainrnent of the desired results;satisfactorydepositsbeingobtained from as low a current density'as10amp's. per' square foot and from as high as 200' amps. per squarefoot. Similarly the temperature of the'solution duringplating isnotsharply critical, good resultsbeinggenerally obtained inthe range offrom about to F. Preferred pH ranges are between about 2.5 and 5 pH.

No completely satisfactory method of causing an antimony electrodeposittoadhere tosteel directlyisknown, so far as I am" aware; here well to;steel; and' inaccordance with the present invention, antimony can bemade to adhere well to lead, tin or silver or alloys oftwo. or morethereof and exhibit semibrightness or full bright-ness by the inclusionin the plating solution of the aqueous, acid fluoride type from whichdeposits on lead, tin-or; silver are to'be'taken, of the novel additionagents described herein. Lustrous useful deposits directly on roughenedsteel'(e. g. etched or sand blasted) can also be produced according tothe present invention.

Having'thus describedthe'invention; what is claimed is:

1. In a process for theelectrodeposition of antimony froma platingsoluti'oncontaining' the antimony primarily as the'soluble-fluoride, thestep of:electrolyzing said solution between an anoderand a cathodewherein said solution containsan aromatic sulfonamide and a heterocyclicnitrogen'containing compound having at least one 6-membered ring, saidaromatic sulfonamide and heterocyclic nitrogen containing:compound-being contained in said solution in amounts sufiicient toproduce an antimony deposit of enhanced brightness.

2. A process according to claim 1 wherein said aromatic sulfonamide iss'el'ecte'd from' the class consisting of benzene sulfonamide, toluenesulfonamide, dibenzene sulfonamide, dibenzene sulfonamide ether andBi-(di-benzene sulfonamide) 3. A process according-toiclaim- 1 whereinsaid heterocyclic nitrogen containing compound is selected from theclass consistingof pyridine, di-pyridyl, N-methyl quinoliniummethosulfate, 2,6-dimethyl quinoline, N-methyl quinaldine methosulfate,N-methyl-2-carboxy quinolinium methyl sulfate and'B-naphthoquinoline.

4. A processaccordingtoclaim1 wherein said aromaticsulfonamideis-selectedfrom-the'class consisting of benzene sulfonamide,toluenesulfonamide, di-benzene sulfonamide, di-benzene sulfonamide etherand Bi-(di-benzene sulfonamide) and wherein said heterocyclic nitrogencontaining compound is selected from'the class consisting of pyridine,di-pyridyl, N-methyl quinolinium methosulfate, 2,6-dimethylzquinoline,N-methyl quinaldine methosulfate, N-methyl-Z-carboxy quinolinium methylsulfate and fl-naphthoquinoline. I

5. In aprocess for the electrodeposition of antimony fromaplatingsolution containingthe antimony primarily as a soluble fiuoridethestep of electrolyzing said solution between an anode and a cathodewherein said solution contains an aromatic sulfonamide, a heterocyclicnitrogen containing compound having at least one 6-membered ring, and asoluble copper salt, said aromatic sulfonamide, heterocyclic nitrogencontaining compound, and soluble copper salt being contained in saidsolution in amounts sufficient toproduce anantimony deposit of enhancedbrightness.

6. A process according'to'claim 5 wherein said aromatic sulfonamide isselected from the'class consisting ofbenzene sulfonamide;toluene'sulfonamide, di-benzene sulfonamide, di-benzene sulfonamideether and Bi-(dibenzene sulfonamide) However lead, tin, and silver ad-7. A process according to claim 5, wherein said heterocyclic nitrogencontaining compound is selected from the class consisting of pyridine,di-pyridyl, N-methyl quinolinium methosulfate, 2,6-dimethyl quinoline,N-methyl quinaldine methosulfate, N-methyl-2carboxy quinolinium methylsulfate and 8-naphthoquinoline.

8. A process according to claim 5 wherein said aromatic sulfonamide isselected from the class consisting of benzene sulfonamide, toluenesulfonamide, di-benzene sulfonamide, di-benzene sulfonamide ether andBi-(dibenzene sulfonamide) and wherein said heterocyclic nitrogencontaining compound is selected from the class consisting of pyridine,di-pyridyl, N-methyl quinolinium methosulfate, 2,6 dimethyl quinoline, Nmethyl quinaldine methosulfate, N-methyl 2 carboxy quinolinium methylsulfate and fi-naphthoquinoline.

9. A process according to claim 8 wherein the soluble copper salt isselected from the class consisting of copper fluoride, copper chlorideand copper sulfate.

10. In a process for the electrodeposition of antimony from a platingsolution containing the antimony primarily as the soluble fluoride, thestep of electrolyzing said solution between an anode and a cathodewherein said solution contains an aromatic sulfonamide, a heterocyclicnitrogen containing compound having at least one 6-membered ring, andcoumarin, said aromatic sulfonamide, heterocyclic nitrogen containingcompound and coumarin being contained in said solution in amountssuflicient to produce an antimony deposit of enhanced brightness.

11. A process according to claim 10 wherein said aromatic sulfonamide isselected from the class consisting of benzene sulfonamide, toluenesulfonamide, di-benzene sulfonamide, di-benzene sulfonamide ether andBi-(dibenzene sulfonamide) 12. A process according to claim 10 whereinsaid heterocyclic nitrogen containing compound is selected from theclass consisting of pyridine, di-pyridyl, N-rnethyl quinoliniummethosulfate, 2,6-dimethyl quinoline, N-methyl quinaldine methosulfate,N-methyl-Z-carboxy quinolinium methyl sulfate and fl-naphthoquinoline.

13. A process according to claim 10 wherein said aromatic sulfonamide isselected from the class consisting of benzene sulfonamide, toluenesulfonamide, di-benzene sulfonamide, di-benzene sulfonamide ether andBi-(dibenzene sulfonamide) and wherein said heterocyclic nitrogencontaining compound is selected from the class consisting of pyridine,di-pyridyl, N-methyl quinolinium methosulfate, 2,6-dimethyl quinoline,N-methyl quinaldine methosulfate, N-methyl 2 carboxy quinolinium methylsulfate and fi-naphthoquinoline.

14. In a process for the electrodeposition of antimony from a platingsolution containing the antimony primarily as a soluble fluoride, thestep of electrolyzing said solution between an anode and a cathodewherein said solution contains an aromatic sulfonamide, a heterocyclicnitrogen containing compound having at least one 6-membered ring, and asoluble zinc salt, said aromatic sulfonamide, heterocyclic nitrogencontaining compound, and soluble zinc salt being contained in saidsolution in amounts suflicient to produce an antimony deposit ofenhanced brightness.

15. A process according to claim 14 wherein said aromatic sulfonamide isselected from the class consisting of benzene sulfonamide, toluenesulfonamide, di-benzene sulfonamide, di-benzene sulfonamide ether andBi-(dibenzene sulfonamide).

16. A process according to claim 14 wherein said heterocyclic nitrogencontaining compound is selected from the group consisting of pyridine,di-pyridyl, N-methyl quinolinium methosulfate, 2,6-dimethy1 quinoline,N-methyl quinaldine methosulfate, N-methyl 2 carboxy quinolinium methylsulfate and fi-naphthoquinoline.

17. A process according to claim 14 wherein said aromatic sulfonamide isselected from the group consisting of benzene sulfonamide, toluenesulfonamide, di-benzene sulfonamide, di-benzene sulfonamide ether andBi-(dibenzene sulfonamide) and wherein said heterocyclic nitrogencontaining compound is selected from the class consisting of pyridine,di-pyridyl, N-methyl quinolinium methosulfate, 2,6-dimethyl quinoline,N-methyl quinaldine methosulfate, N methyl 2 carboxy quinolinium methylsulfate and B-naphthoquinoline.

18. A process according to claim 17 wherein said soluble zinc salt isselected from the class consisting of zinc chloride, zinc sulfate andzinc fluoride.

19. In a process for the electrodeposition of antimony from a platingsolution containing the antimony primarily as a soluble fluoride, thestep of electrolyzing said solution between an anode and a cathodewherein said solution conatins a heterocyclic nitrogen containingcompound having at least one 6-membered ring, and another co-operatingbrightening agent selected from the group consisting of aromaticsulfonamides, sulfonates, and sulfinates, said heterocyclic nitrogencontaining compound and co-operating brightening agent being containedin said solution in amounts suflicient to produce an antimony deposit ofenhanced brightness.

20. A process according to claim 19 wherein said heterocyclic nitrogencontaining compound is selected from the class consisting of pyridine,di-pyridyl, N-methyl quinolinium methosulfate, 2,6-dimethyl quinoline,N-methyl quinaldine methosulfate, N-methyl-Z-carboxy quinolinium methylsulfate and ,B-naphthoquinoline.

21. An antimony plating solution comprising antimony primarily as thesoluble fluoride, di-benzene sulfonamide in amounts ranging from about.25 to about 3 grams per liter, and a heterocyclic nitrogen containingcompound having at least one 6-membered ring selected from the classconsisting of pyridine, di-pyridyl, 2,6-di-methyl quinoline, andN-methyl quinaldine methosulfate in amounts ranging from about .01 to 1gram per liter.

22. An antimony plating solution comprising antimony primarily as thesoluble fluoride, di-benzene sulfonamide in amounts ranging from about.75 to 1.5 grams per liter, a heterocyclic nitrogen containing compoundhaving at least one 6-membered ring selected from the group con sistingof N-methyl quinolinium methosulfate, N-methyl quinaldine methosulfate,ranging in amounts from about .01 to .2 gram per liter and copper inamounts ranging from about .003 to .1 gram per liter.

23. An antimony plating solution comprising antimony primarily as thesoluble fluoride, di-benzene sulfonamide in amounts ranging from about.75 to 2.5 grams per liter, a heterocyclic nitrogen containing compoundhaving at least one 6-membered ring selected from the class consistingof pyridine and N-methyl-Z-carboxy quinolinium methyl sulfate in amountsranging from about .01 to about 1.5 grams per liter and coumarin inamounts ranging from about .03 to .35 gram per liter.

24. An antimony plating solution comprising antimony primarily as asoluble fluoride, an aromatic sulfonamide, a heterocyclic nitrogencontaining compound having at least one 6-membered ring, and a solublezinc compound, said aromatic sulfonamide, heterocyclic nitrogencontaining compound, and zinc compound being contained in such solutionin amounts sufiicient to produce an antimony deposit of enhancedbrightness during electrodeposition of antimony therefrom.

25. An antimony plating solution comprising antimony primarily as thesoluble fluoride, di-benzene sulfonamide in amounts ranging from about.25 to 6 grams per liter, a heterocyclic nitrogen containing compoundhaving at least one 6-membered ring in amounts ranging from about .01 to2 grams per liter and a soluble zinc compound in amounts equivalent tothe zinc of about .03 to 3.5 grams per liter.

26. An antimony plating solution comprising antimony primarily as asoluble fluoride, a heterocyclic nitrogen containing compound having atleast one 6-membered ring, and a co-operating brightening agent selectedfrom a-nd si1lfinates, said lie'terocyclic nitrogen c'ontainingconipound and era-operatingbrightening agent-being contained in saidsolution inam'ounts su'ffieient' to produce an'timonydeposit of enhancedbrightness during electrodeposition of antimony therefrom;

27. A solution according to claim 26 wherein said'heterocyclic nitrogencontaining compound is' selected from the class consisting of pyr idine,di-pyridyl, N-methyl' quinolinium methosulfate 2 ;6-dimethyl"quinoli'ne, N-methyl quina'ldine rnethosulfate, N-l'nethyl-2 carboxyquinolinium methyl sulfate and fi=naplithoquinoline-.-

I2 28-; A solution accordingto claim 27 wherein said hete're'dyiilidriitrogen containin compound is resent in amnu-nts rnging front about.01 to 3.5 gram's p'er liter.

References- Citedin'the'file of this patent UNITED STATES PATENTS2-",'7'1-1;010 Karash in June 21, 1955 7 OTHER REFERENCES Soderlv'er-get aL, Plating-v01; 37 (1950 page 257.

1. IN A PROCESS FOR THE ELECTRODEPOSTION OF ANTIMONY FROM A PLATINGSOLUTION CONTAINING THE ANTIMONY PRIMARILYY AS THE SOLUBLE FLUORIDE, THESTEP OF ELECTROLYZING SAID SOLUTION BETWEEN AN ANODE AND A CATHODEWHEREIN SAID SOLUTION CONTAINS AN AROMATIC SULFONAMIDE AND AHETEROCYCLIC NITROGEN CONTAINING COMPOUND HAVING AT LEAST ONE 6-MEMBEREDRING, SAID AROMATIC SULFONAMIDE AND HETEROCYCLIC NITROGEN CONTAININGCOMPOUND BEING CONTAINED IN SAID SOLUTION IN AMOUNTS SUFFICIENT TOPRODUCE AN ANTIMONY DEPOSIT OF ENHANCED BRIGHTNESS.